linux-kernel - Re: [PATCH 3/9] arm64: dts: allwinner: pinebook: Remove unused AXP803 regulators

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Date:   Fri, 24 Jan 2020 15:11:29 -0800
From:   Vasily Khoruzhick <anarsoul@...il.com>
To:     Maxime Ripard <maxime@...no.tech>
Cc:     Samuel Holland <samuel@...lland.org>,
        Mark Rutland <mark.rutland@....com>,
        Chen-Yu Tsai <wens@...e.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-sunxi <linux-sunxi@...glegroups.com>,
        Rob Herring <robh+dt@...nel.org>,
        arm-linux <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 3/9] arm64: dts: allwinner: pinebook: Remove unused AXP803 regulators

On Fri, Jan 24, 2020 at 8:36 AM Maxime Ripard <maxime@...no.tech> wrote:
>
> On Tue, Jan 21, 2020 at 09:14:02PM -0600, Samuel Holland wrote:
> > On 1/21/20 3:05 AM, Maxime Ripard wrote:
> > > On Sun, Jan 19, 2020 at 10:30:58AM -0600, Samuel Holland wrote:
> > >> The Pinebook does not use the CSI bus on the A64. In fact it does not
> > >> use GPIO port E for anything at all. Thus the following regulators are
> > >> not used and do not need voltages set:
> > >>
> > >>  - ALDO1: Connected to VCC-PE only
> > >>  - DLDO3: Not connected
> > >>  - ELDO3: Not connected
> > >>
> > >> Signed-off-by: Samuel Holland <samuel@...lland.org>
> > >> ---
> > >>  .../boot/dts/allwinner/sun50i-a64-pinebook.dts   | 16 +---------------
> > >>  1 file changed, 1 insertion(+), 15 deletions(-)
> > >>
> > >> diff --git a/arch/arm64/boot/dts/allwinner/sun50i-a64-pinebook.dts b/arch/arm64/boot/dts/allwinner/sun50i-a64-pinebook.dts
> > >> index ff32ca1a495e..8e7ce6ad28dd 100644
> > >> --- a/arch/arm64/boot/dts/allwinner/sun50i-a64-pinebook.dts
> > >> +++ b/arch/arm64/boot/dts/allwinner/sun50i-a64-pinebook.dts
> > >> @@ -202,9 +202,7 @@
> > >>  };
> > >>
> > >>  &reg_aldo1 {
> > >> -  regulator-min-microvolt = <2800000>;
> > >> -  regulator-max-microvolt = <2800000>;
> > >> -  regulator-name = "vcc-csi";
> > >> +  regulator-name = "vcc-pe";
> > >>  };
> > >
> > > If it's connected to PE, I'd expect the voltage to be at 3.3v?
> >
> > If we provide voltage constraints, the regulator core will enable the regulator
> > and set its voltage at boot. That seems like a bit of a waste.
>
> I'm not sure the regulator core enables them if there's neither
> regulator-boot-on nor regulator-always-on.
>
> > I don't think the voltage really matters, since nothing is plugged in to the
> > port. ALDO1 can't go over 3.3V anyway, so even if it does get turned on for some
> > reason, nothing will get damaged.
>
> Looking at the schematics, it looks like the PE pins are connected to
> the front-facing camera?

The only camera on Pinebook is UVC

>
> Maxime
>
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> linux-arm-kernel@...ts.infradead.org
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